HTS Chapters 54 and 55 subdivide fibers first by whether they are filament or staple, then by polymer type — polyester, nylon, acrylic, polypropylene, viscose rayon, lyocell, and others each occupy distinct headings. Getting the polymer chemistry wrong at the 6-digit level can place a shipment in the wrong heading entirely, affecting both duty rates and any applicable trade-remedy orders.

Artificial fibers derived from cellulose (rayon, lyocell, modal) are purely industrial commodities with no mandatory admissibility review, but they do require accurate fiber-content labeling under the Textile Fiber Products Identification Act if sold at retail in the US. For bulk industrial imports, standard CBP entry documentation and correct HTS classification are the primary compliance requirements.